Packaging sheet material for packaging pourable food products

Abstract

A sheet material ( 2 ) for packaging food products and having a number of fold lines ( 4 ) formed by compression creasing, so that the fold lines ( 4 ) have a recessed profile on the face ( 23 ) of the material ( 2 ) eventually facing outwards of the package ( 17 ) and bearing a printed decoration ( 5 ), and a nonconvex profile on the opposite face ( 25 ); the decoration ( 5 ) has a printed area ( 36 ) at least partly enclosing one or more fold lines ( 37 ), so as to define, with them and by contrast, an optically detectable register mark ( 18 ).

1 . A packaging sheet material for packaging pourable food products and having a number of fold lines wherein said fold lines are compression lines having a recessed profile on a first face of the material, and a nonconvex profile on a second face of said material.  
     
     
         2 . A material as claimed in  claim 1 , comprising at least one optically detectable register mark on said first face.  
     
     
         3 . A material as claimed in  claim 1 , wherein said register mark is at least partly defined by said compression lines.  
     
     
         4 . A material as claimed in  claim 1 , having a decoration printed on said first face.  
     
     
         5 . A material as claimed in  claim 4 , wherein said decoration comprises at least one printed area at least partly enclosing said compression lines and defining, with them and by contrast, said register mark.  
     
     
         6 . A material as claimed in  claim 1 , wherein said register mark comprises at least two parallel segments, and a sloping segment interposed between the parallel segments.  
     
     
         7 . A material as claimed in  claim 6 , wherein said register mark comprises four segments arranged in the form of a square, and a sloping segment along the diagonal of the square.  
     
     
         8 . A material as claimed in  claim 1 , wherein said compression lines are defined, towards said first face of the material, by steep sides.  
     
     
         9 . A material as claimed in  claim 1 , wherein said compression lines are of a depth ranging between 30% and 60% of the thickness of the material.  
     
     
         10 . A material as claimed in  claim 3 , wherein said compression lines are of a depth equal to about 50% of the thickness of the material.  
     
     
         11 . A method of producing a sheet material for packaging food products and having a number of fold lines comprising a compression creasing step in which said material is compressed between a creasing roller, acting on a first face of said material and having a number of projections for producing said fold lines in the form of compression lines, and a substantially smooth reaction roller acting on a second face of said material.  
     
     
         12 . A method as claimed in  claim 11 , wherein said projections of said creasing roller are of a height ranging between 50 and 90% of the thickness of said material.  
     
     
         13 . A method as claimed in  claim 12 , wherein said projections of said creasing roller are of a height substantially equal to 80% of the thickness of said material.  
     
     
         14 . A method as claimed in  claim 11 , comprising a printing step to print a decoration on said first face of said material.  
     
     
         15 . A method as claimed in  claim 14 , wherein said printing step produces a printed area enclosing at least a portion of said compression lines to define an optically detectable register mark.